In this study, a shape of connector on seismic reinforced strip, which did not cause any physical damage to concrete column and can repair and reinforcement was decided by using nonlinear finite element analysis. Load displacement was applied on the concrete attached by strip. Stress distribution of connector by extension of concrete were checked. Through stress distribution of this analysis results, the most favorable shape was selected as a shape of the connector.

도시화가 가속화됨에 따라 도로주변의 주거지역 개발 및 교통량 증가로 도로소음피해가 점차 증가하고 있다. 이에 소음피해의 대책으로 방음벽 설치 수요가 증가하고 있는 추세이다. 방음벽은 특성 및 재질에 따라 다양한 형태로 분류되며 크게 흡음형과 반사형 방음벽으로 구분 할 수 있다. 이중 반사형 방음벽의 경우 주변경관과의 조화성이 높으며, 특히 투명형의 경우 조망권 확보가 유리하다는 장점이 있어 최근 투명형 방음벽의 설치요구가 증가하고 있다. 그러나 반사소음의 영향을 받을 우려가 있는 지역의 경우 설치에 제한이 있다는 단점이 있다. 본 연구에서는 반사소음 저감을 위하여 방음벽 형상에 따른 소음저감 효과를 수학적 모델을 이용하여 시뮬레이션 하였다. 소음저감 목표지점은 방음벽 맞은편 5m(R1), 15m(R2) 높이와 도로내부(R3)등 3개 지점으로 선정하여 일반 평판형 방음벽대비 형상방음벽의 반사소음저감을 평가하였다. 시뮬레이션 결과 R1지점에서는 평판형 대비 형상방음벽에서 2.2 dB(A)의 소음이 저감되었으며 R2지점은 0.7 dB(A)의 소음이 증가하였고 R3지점은 소음의 증감이 없었다. 주파수별로는 R1과 R2의 경우 63 Hz 부터 8 KHz까지 주파수별 반사소음차이는 없으나, R3의 경우 63Hz에서 1.3dB(A)가 증가하였고, 8000 Hz에서는 0.5 dB(A)의 소음이 감소하였다. 결론적으로, 방음벽에 형상을 둠에 따라 반사소음 저감효과가 있음을 확인하였으며 최적형상 방음벽을 개발함으로써 반사음 문제해결이 가능할 것으로 사료된다.

굵은골재의 입자 특성은 골재혼합물의 다짐도, 아스팔트 콘크리트 또는 시멘트 콘크리트 혼합물의 역 학적 특성에 큰 영향을 미치는 중요한 인자이다. 도로포장 재료로서 골재의 특성을 최대한 활용하기 위한 골재의 최적배합설계를 결정하기 위해서는 다양한 골재의 단위중량, 크기뿐만 아니라 역학적으로 설명될 수 있는 형상적 특성이 정량화할 필요가 있는데, 이를 위하여 사용되는 다짐밀도실험은 많은양의 실내실험을 요구하는 단점이 있다. 이산요소법 또는 개별요소법(Discrete Element Method, DEM)은 유한요소법(Finite Element Mehtod, FEM)과는 달리 이산되어 있는 재료의 거동을 수치적인 방법으로 모사할 수 있는 장점이 있으며, 이를 활용한 연구가 다양한 분야에서 이루어지고 있다. 그러나 아스팔트 혼합물에 관련된 분야에서는 골재자체의 특성이나 다짐밀도를 분석하기 위한 연구보다는 혼합물의 피로특성을 분 석하는 연구를 중심으로 이루어져 골재다짐에 관련된 연구는 많이 진행되지 못하였다. 본 연구에서는 골재의 형상적 특성을 반영한 역학적 물성을 정량화하고자 이미지 분석(Image Analysis)결과, 골재자체의 단위중량 및 무게 등의 기초물성 실험결과, 상용 DEM 소프트웨어, 문헌에서 확인된 역학적 인자 및 등가구형지름(Equivalent Sphere Diamter) 개념을 이용하여 골재슬럼프 실험에 서의 골재의 거동을 시뮬레이션하였으며, 높이 및 퍼진 골재의 지름을 기준으로 시뮬레이션 실험과 실제 실험결과와 유사한 것을 확인하였다. 본 연구의 결과는 x-ray CT 등을 이용한 향후 3D 골재형상 이미지 또는 혼합물 속의 골재의 분포 등을 이용한 골재다짐밀도 모형과 Flow Modeling Software 등과의 coupling을 통하여 시멘트 콘크리트의 배합설계법개발에 적용되기 위하여 지속적으로 수행될 예정이다.

Quantum dots(QDs) with their tunable luminescence properties are uniquely suited for use as lumophores in light emitting device. We investigate the microstructural effect on the electroluminescence(EL). Here we report the use of inorganic semiconductors as robust charge transport layers, and demonstrate devices with light emission. We chose mechanically smooth and compositionally amorphous films to prevent electrical shorts. We grew semiconducting oxide films with low free-carrier concentrations to minimize quenching of the QD EL. The hole transport layer(HTL) and electron transport layer(ETL) were chosen to have carrier concentrations and energy-band offsets similar to the QDs so that electron and hole injection into the QD layer was balanced. For the ETL and the HTL, we selected a 40-nm-thick ZnSnOx with a resistivity of 10Ω·cm, which show bright and uniform emission at a 10 V applied bias. Light emitting uniformity was improved by reducing the rpm of QD spin coating.At a QD concentration of 15.0 mg/mL, we observed bright and uniform electroluminescence at a 12 V applied bias. The significant decrease in QD luminescence can be attributed to the non-uniform QD layers. This suggests that we should control the interface between QD layers and charge transport layers to improve the electroluminescence.

본 논문에서는 아이소-지오메트릭 기법을 기반으로 민들린 후판에 대한 형상 설계민감도 해석법을 제시하였다. 아이소-지오메트릭 기법은 정확한 기하학적 형상의 표현, 요소 사이의 높은 연속성 등 바람직한 강점들을 가지고 있으며 궁극적으로는 해석해로의 빠른 수렴성과 정확한 설계민감도를 제공한다. 선형 형상함수를 사용하는 유한요소법과는 달리 아이소-지오메트릭 기법에서는 높은 차수의 NURBS 기저함수를 활용하여 CAD 형상의 법선벡터와 곡률을 정확하게 고려한다. 전단 잠김(Shear locking) 현상을 극복하기 위해서 선택적 감소적분(Selective reduced integration) 기법을 사용하였다. 이 간단한 방법은 복잡한 정식화 과정 없이 정확한 아이소-지오메트릭 형상 설계민감도 해석을 수행한다. 굽힘 문제에 대한 수치예제를 통하여 제안된 아이소-지오메트릭 해석과 유한요소 해석을 비교하였으며, 유한차분 설계민감도와 비교하여 아이소-지오메트릭 형상 설계민감도는 매우 정확함을 확인하였다.

目前關羽信仰和關羽崇拜已經成爲中國社會的一種特殊文化現象。關羽 形象隨着三國歷史而走進中國社會, 他的故事也在悠久的中國歷史和廣範的 地區上流傳了將近兩千年。隨着時代的推移, 關羽形象也有了變化。在關羽 形象演變過程中, 長篇歷史演義小說≪三國演義≫所塑造的歷史人物關羽完 成了其形象的文學定型。本論文考察≪三國演義≫所塑造的關羽人物形象的 特點, 以探討了在關羽崇拜文化現象上其特點所反映的價値和意味。

The electrical properties and surface morphology changes of a silicon wafer as a function of the HF concentration as the wafer is etched were studied. The HF concentrations were 28, 30, 32, 34, and 36 wt%. The surface morphology changes of the silicon wafer were measured by an SEM (80˚ tilted at ×200) and the resistivity was measured by assessing the surface resistance using a four-point probe method. The etching rate increased as the HF concentration increased. The maximum etching rate 27.31 μm/min was achieved at an HF concentration of 36 wt%. A concave wave formed on the wafer after the wet etching process. The size of the wave was largest and the resistivity reached 7.54 ohm·cm at an 30 wt% of HF concentration. At an HF concentration of 30 wt%, therefore, a silicon wafer should have good joining strength with a metal backing as well as good electrical properties.

구비문학에는 많은 인물과 주제와 소재가 존재한다. 또한 이것들은 이야기를 구성하는 데 중요한 역할을 하며, 이러한 요소를 활용하여 그들의 의식을 표현할 수 있다. 그 중에서 인물은 이야기의 구성상 가장 핵심적이고 중요한 역할을 한다. 따라서 본고에서는 서울과 경기지역에 나타난 통치자를 중심으로 살펴본 결과 각 지역마다 통치자의 인물형상이 보편화되어 드러나는 것이 아니라 지역적 특색에 맞게 통치자의 형상이 나타나고 있었다. 즉, 서울권은 보다 사실적인 묘사를 통해 평민의식을 실현했으며, 여주, 용인, 남양주 등과 같은 지역은 풍수와 관련된 설화가 많은데 이는 왕릉이 주로 분포된 곳이기 때문에 이러한 풍수사상이 평민에게 스며들었고, 수원․화성의 통치자는 대부분 정조가 등장하는데 이는 역사적으로 정조가 아버지인 장헌세자를 그리워 자주 찾았다는 점에서 그 이유를 찾을 수 있다. 이와 같이 통치자의 형상이 각 지역의 역사적, 사회적 특징에 맞게 구비문학으로 전승되고 있음을 알 수 있다.

PURPOSES: Current theories for composite structures are too difficult for design engineers for construction. The purpose of this paper is to demonstrate to the practicing engineers, how to apply the advanced composite materials theory to the road structures. METHODS: Some laminate orientations have decreasing values of D16, B16, D26 and B26 stiffnesses as the ply number increases. The plate aspect ratio considered is from 1 to 5. In order to study the effect of Mx on the equilibrium equations, two cases are considered. Mx term is considered or neglected. RESULTS: Most of the road structures have high aspect ratios, for such cases further simplification is possible by neglecting the effect of the longitudinal moment terms. CONCLUSIONS: Most of the road structures have plate aspect ratios higher than 2. It is concluded that, for all boundary conditions, neglecting the longitudinal moment(Mx) terms is acceptable if the aspect ratio (a/b) is equal to or higher than 2. This conclusion gives good guide line for design of the road structures.

The shape of tire footprint is one of the important factor which affects to the performance of tire such as handling, ride and wear. In this study, the effect of the stiffness for tire footprint is investigated. Some tires on the market were selected and tested the vertical stiffness, lateral stiffness by stiffness measuring system. And the contact length, contact width and contact area are tested, too. The contact width and length is reduced by the increase of the tire stiffness. According to the change of the tire stiffness, the leading edge and trailing edge in the footprint have a different shape.

This paper presents the design, fabrication and performance of a reinforced concrete beam strengthened by GFRP box plate and its possibility for structural rehabilitations. The load capacity, ductility and failure mode of reinforced concrete structures strengthened by FRP box plate were investigated and compared with traditional FRP plate strengthening method. This is intended to assess the feasibility of using FRP box plate for repair and strengthening of damaged RC beams. A series of four-point bending tests were conducted on RC beams with or without strengthening FRP systems the influence of concrete cover thickness on the performance of overall stiffness of the structure. The parameters obtained by the experimental studies were the stiffness, strength, crack width and pattern, failure mode, respectively. The test yielded complete load-deflection curves from which the increase in load capacity and the failure mode was evaluated.

For fabricating silicon solar cells with high conversion efficiency, texturing is one of the most effective techniques to increase short circuit current by enhancing light trapping. In this study, four different types of textures, large V-groove, large U-groove, small V-groove, and small U-groove, were prepared by a wet etching process. Silicon substrates with V-grooves were fabricated by an anisotropic etching process using a KOH solution mixed with isopropyl alcohol (IPA), and the size of the V-grooves was controlled by varying the concentration of IPA. The isotropic etching process following anisotropic etching resulted in U-grooves and the isotropic etching time was determined to obtain U-grooves with an opening angle of approximately 60˚. The results indicated that U-grooves had a larger diffuse reflectance than V-grooves and the reflectances of small grooves was slightly higher than those of large grooves depending on the size of the grooves. Then amorphous Si:H thin film solar cells were fabricated on textured substrates to investigate the light trapping effect of textures with different shapes and sizes. Among the textures fabricated in this work, the solar cells on the substrate with small U-grooves had the largest short circuit current, 19.20 mA/cm2. External quantum efficiency data also demonstrated that the small, U-shape textures are more effective for light trapping than large, V-shape textures.

A level set based topological shape optimization method for nonlinear structure considering hyper-elastic problems is developed. To relieve significant convergence difficulty in topology optimization of nonlinear structure due to inaccurate tangent stiffness which comes from material penalization of whole domain, explicit boundary for exact tangent stiffness is used by taking advantage of level set function for arbitrary boundary shape. For given arbitrary boundary which is represented by level set function, a Delaunay triangulation scheme is used for current structure discretization instead of using implicit fixed grid. The required velocity field in the actual domain to update the level set equation is determined from the descent direction of Lagrangian derived from optimality conditions. The velocity field outside the actual domain is determined through a velocity extension scheme based on the method suggested by Adalsteinsson and Sethian(1999). The topological derivatives are incorporated into the level set based framework to enable to create holes whenever and wherever necessary during the optimization.

A topology optimization method for phononic crystals is developed for the design of sound barriers, using the level set approach. Given a frequency and an incident wave to the phononic crystals, an optimal shape of periodic inclusions is found by minimizing the norm of transmittance. In a sound field including scattering bodies, an acoustic wave can be refracted on the obstacle boundaries, which enables to control acoustic performance by taking the shape of inclusions as the design variables. In this research, we consider a layered structure which is composed of inclusions arranged periodically in horizontal direction while finite inclusions are distributed in vertical direction. Due to the periodicity of inclusions, a unit cell can be considered to analyze the wave propagation together with proper boundary conditions which are imposed on the left and right edges of the unit cell using the Bloch theorem. The boundary conditions for the lower and the upper boundaries of unit cell are described by impedance matrices, which represent the transmission of waves between the layered structure and the semi-infinite external media. A level set method is employed to describe the topology and the shape of inclusions. In the level set method, the initial domain is kept fixed and its boundary is represented by an implicit moving boundary embedded in the level set function, which facilitates to handle complicated topological shape changes. Through several numerical examples, the applicability of the proposed method is demonstrated.

Finite element analysis is to approximate a geometry model developed in computer-aided design(CAD) to a finite element model, thus the conventional shape design sensitivity analysis and optimization using the finite element method have some difficulties in the parameterization of geometry. However, isogeometric analysis is to build a geometry model and directly use the functions describing the geometry in analysis. Therefore, the geometric properties can be embedded in the NURBS basis functions and control points so that it has potential capability to overcome the aforementioned difficulties. In this study, the isogeometric structural analysis and shape design sensitivity analysis in the generalized curvilinear coordinate(GCC) systems are discussed for the curved geometry. Representing the higher order geometric information, such as normal, tangent and curvature, yields the isogeometric approach to be the best way for generating exact GCC systems from a given CAD geometry. The developed GCC isogeometric structural analysis and shape design sensitivity analysis are verified to show better accuracy and faster convergency by comparing with the results obtained from the conventional isogeometric method.

Welded Unreinforced Flange-Welded Web (WUF-W) connection is one of Special Moment Frame (SMF) specified in ANSI/AISC-358. From the experimental test of WUF-W connection specimens conducted by the previous study, fracture occurred in the beam flange before achieving total inter-story drift angle of 0.04radian required for Special Moment Frames (SMF) system even though the specimens satisfied the design and detailing requirement specified in ANSI/AISC-358. These results are estimated as problem of the access hole geometry. In this study, a full-scale WUF-W connection specimen was made with a modified access hole geometry, and tested with the same test setting and loading as the previous test. From test results, the deformation capacity of the tested WUF-W connection specimen exceeded 4%, which is required for connections in SMF system. Comparing with the WUF-W specimens of the previous study, the strain demand of the beam flange in the tested specimen was decreased and energy dissipation capacity of the specimen was improved.

The researches related to active control systems utilizing superelastic shape memory alloys (SMA) have been recently conducted to reduce critical damage due to lateral deformation after severe earthquakes. Although Superelastic SMAs undergo considerable inelastic deformation, they can return to original conditions without heat treatment only after stress removal. We can expect the mitigation of residual deformation owing to inherent recentering characteristics when these smart materials are installed at the part where large deformation is likely to occur. Therefore, the primary purpose of this research is to develop concentrically braced frames (CBFs) with superelastic SMA bracing systems and to evaluate the seismic performance of such frame structures. In order to investigate the inter-story drift response of CBF structures, 3- and 6-story buildings were design according to current design specifications, and then nonlinear time-history analyses were performed on numerical 2D frame models. Based on the numerical analysis results, it can be comparatively verified that the CBFs with superelastic SMA bracing systems have more structural advantages in terms of energy dissipation and recentering behavior than those with conventional steel bracing systems.